Dan & Theresa use these balls with all of their clients, as an alternative to using metal or free weights in some of their work routines.  These balls are easily grasped because of their slight give, and can be used by every level of athlete.  They enhance strength and endurance by helping isolate specific muscle groups during training. They work effectively for hands, biceps, triceps, abdominals, lunges, leg curls and stretching. In years of experience training clients, Dan & Theresa have found these weighted balls to be the best weighted balls on the market, due to comfort in handling, ease of use, & versitility of exercises available, due to the  strap attached to the ball.  This is a must have for any workout program!